Is the the MH lighting your going to stick with? While the reflectors are great, I think the ballast and bulb could use some upgrading.
PFO HQI Magnetic dual 250w ballast with
dual 250w 20k radiums would be amazing on that tank, and probably reduce your need for the VHOs. Or if your shooting for most growth, go like I did,
XM10ks and use your VHOs for actinics. I think the
XM10k is a great bulb for growth, but if you want best coloring nothing beats the
Radium 20k. I have yet to see a 14k/15k bulb that was any good. You seem to sacrifice both growth and coloring when you use those bulbs.. they have the PAR output of a 20k bulb but looks more like a 10K in coloring. JMHO of course.